Weapons fallout

Studies of the transfer of radiocerium into various plant parts via the soil-root pathway are summarized in Table 6. Other laboratory and field studies employing tracer radiocerium or nuclear weapons fallout simulants are summarized in Tables 7 and 8. In general, the cereal grains and vegetable pulp showed plant-to-soil concentration factors (radioactivity per gram of dry plant material/radioactivity per gram of... 

Concentratons of Sr in people living in New York City between 1953 and 1959 who were exposed to nuclear weapons fallout were reported by Kulp and Schulert (1962). They suggested that the distribution of observed values was well fit by a log-normal distribution that had a geometric standard deviation of about 1.7. The Federal Radiation Council (FRC, 1961), after review of the accumulated data on Sr in human bone, concluded that a log-normal distribution was the appropriate description of the distribution of this age-controlled, exposuretime controlled population. The main exposure to Sr from fallout was by way of ingestion. 

The radiological impact of the Chernobyl debris compared with that from nuclear weapons fallout. Journal of Environmental Radioactivity, 6,151-62. Aarkrog, A. Lippert, J. (1971) Direct contamination of barley with 51 Cr,59Fe,58 Co, 65Zn, 203Hg and 210Pb. Radiation Botany, 11, 463-72. 

Phillips F. M., Mattick J. L., Duval T. A., Elmore D., and Kubik P. W. (1988) Chlorine-36 and tritium from nuclear weapons fallout as tracers for long-term liquid and vapor movement in desert soils. Water Resour. Res. 24, 1877-1891. 

There is a disadvantage with the use of environmental samples to assess the radionuclide concentrations in the environment. This arises since there is the potential for contamination of such samples from previously deposited material. This material may or may not originate from the source of interest and there may be significant contributions from Chernobyl and weapons fallout. Such contamination pathways include soil splash, the deposition of resuspended material and root uptake. 

Cesium-137 and strontium-90 from nuclear weapon fallout using tobacco as an example Z. Lebensm. 

In Japanese watersheds, Cs is mainly derived from the radioactive fallout of nuclear fission during weapon tests in the atmosphere (Wise, 1980). The majority of the tests were conducted during the period 1950-1962. The total injection of Cs to the atmosphere from these tests is estimated to be 960 PBq (lO Bq) (UNSCEAR, 1982). The Chernobyl accident in 1986 resulted in several times greater fallout of Cs in European countries compared to the weapon fallout (Nuclear Energy Agency, 1995). However, it increased only about 4% of the integrated deposition density of Cs in Japan at the time of accident (1986). 

Nuclear weapons tests have released large amounts of radionuclides into the atmosphere, which through their own weight or by rain have been carried to the earth s surface. Geophysics has made use of this weapon "fallout". By measurements on T (as HTO water). 

The deposition of Tc from weapon fallout has been estimated to be 540 + 50mBqm at 62°N. Frequently, carpets of mosses and lichens are used as bioindicators for the estimation of deposited radionuclides. The concentration of Tc in lichens (mBq per kg dry weight), the fission yields (Mt) for nuclear weapons testing, and the observed and theoretical Tc/ Cs radionuclide ratios are given in Figure 1. The present Tc/ Cs ratio is expected to be 3.2 X 10 " due to the physical decay of Cs. In general, the observed Tc/ Cs ratio is lower than expected from fission probably due to a shorter residence time for Tc in the lichen carpet. The concentration of Tc and the Tc/ Cs ratio in lichens has increased since 1975. Unusual mixtures of shortlived radioisotopes, e.g., Np and Mo, in fallout... 

The amount or volume of environmental samples needed for analysis for Tc depends on the degree of contamination (i.e., distance to the source) and the sensitivity of the measurement technique (i.e., detection limits). In the Irish Sea watei volumes of 10-50 L may be sufficient, while 50-1001 is needed in the Arctic Seas. For areas contaminated only from weapon fallout, volumes up to 10001 may be needed. Especially in coastal areas or in high production areas filtration of waters through 0.45 pm membrane is recommended, as algal materials, in particular. 

Samples collected in the eastern subtropical North Atlantic in 1969 were used in order to measure the impact of weapons-fallout l in the oceans (Edmonds et al. 1998). The measured I29i/i27i sample was (0.53 0.08) X 10 , being ten times higher compared with... 

Blanks of the swipe sample matrix ( swipe blank ) after each processing step. The swipe blank contains the process blank as well as any U, Pu or interfering elements contained in the swipe material. The cotton wipers chosen for swipe sampling are generally quite low in U content - 1-5 ng per wiper - and the Pu content is not measurable by bulk analysis it is believed to be below 1 fg (the most likely source would be Pu from nuclear weapons fallout). 

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